Such a stator-rotor device (hereinafter also called “device” for the sake of simplicity) is used for example in an electric motor that is integrated in a motor pump unit. It is also conceivable however to use the device in generators.
When the device is used in an electric motor the device comprises windings surrounding the pole cores, through which a respective magnetic field is produced by current flowing through the pole cores. The magnetic field passes through the pole shoes and forms a magnetic dipole in the latter. The dipole can cooperate with the magnets, wherein the magnetic flux passes through the air gap between the pole shoes and the magnets.
It is possible for the stator to include the pole cores and the pole shoes and for the rotor to include the magnets. This situation may however may also be reversed, wherein the stator includes the magnets and the rotor includes the pole cores and the pole shoes.
The largest possible magnetic flux between the pole shoes and the magnets is desired. This requires the use of relatively expensive magnets. However, an inexpensive production of the device is also desirable.